News Release 031
DNR finds evidence of chromium-6 in water treatment additives in Hannibal
Volume 38-031 (For Immediate Release)
Contact: Judd Slivka
JEFFERSON CITY, MO, JAN. 25, 2010 -- Additional results from testing of Hannibal's drinking water treatment processes show traces of total and chromium-6 in commercial additives used to help treat the city's drinking water. Nonetheless, the water remains safe to drink.
The Missouri Department of Natural Resources continues to work with the City of Hannibal, the U.S. Environmental Protection Agency, the Missouri Department of Health and Senior Services and the National Sanitary Foundation to better understand what is happening in Hannibal's public drinking water.
Samples taken of two compounds used during the water treatment process found evidence of chromium-6 in both the alum -- a liquid coagulant used to separate solids from the water -- and the lime aggregate, which is used to balance the pH level of the water. Both of the compounds dissolve in drinking water and the public is never exposed to them in concentrated form.
Chromium levels for the alum were measured as liquid samples, measured as ug/l (parts per billion). Total chromium measurements (measuring all the species of chromium in the water) for the alum were 361 parts per billion; hexavalent chrome levels were estimated to be at 41 parts per billion. There is no health standard for chromium levels in concentrated water additives. Sampling results indicate a total chromium value of less than 2.5 parts per billion after the alum is added, which is below the 100 part per billion federal and state standard for total chromium in the water.
Total chromium levels in the lime aggregate were 46 ug/l (parts per billion); chromium-6 levels were analyzed as solid samples and measured at 6.5 mg/kg (parts per million). Sampling results indicate a total chromium value in the water of less than 2.5 parts per billion after the lime is added, which is below the 100 part per billion federal and state standard for total chromium in the water.
The department's design standards for public water systems require that all chemicals used to treat drinking water shall be certified for drinking water use in accordance with the American National Standards Institute / NSF Standard 60/61. It is the department's understanding that the supplies of both the alum and the lime aggregate are certified by the National Sanitary Foundation, an independent, non-governmental organization which provides product specifications for the additives.
At this time DNR can not determine if these levels of impurities in the additives are acceptable, but has shared all information with the U.S. EPA and the National Sanitary Foundation.
The EPA agrees that the public water delivered meets the health-based standards. At this time, EPA indicates there are no changes being considered to the drinking water standard for chromium.
DNR continues to work with the City of Hannibal, the EPA and DHSS to ensure that Hannibal's water is safe to drink. Hannibal's public drinking water supply has been in and remains in full compliance with Missouri and federal drinking water standards.